Conicovate grinder burr



Dec. 6, 1927.

T. WADLEIGH CONICOVATE GRINDER BURR Filed June 7. 1926 W i \2 M m m 2 M m W 6 Patented Dec. 6, 1927. V

1,651,425 PATENT OFFICE.

THEODORE WADLEIGH, or soMERsiowA.

' coixrroovn'rr GRINDER BURR.

Application filed June 7;

My invention relates to that type of'burrs for grinding mills, particularly for grinding feed such as car corn, which are of generally conicalform and are arranged in either upright or'horizontal position in the mill',zand I have modified thisconical'form for certain purposes which will be made clear, and produced a form of burr which I have termed conicovate. i

This type of mill includes an outer stationary urr and an inner rotating burr, and one of these members, generally the 1nner burr, 1s ad ustablelongitudinally mor der to adjust the finenessof reduction or to compensate for wear. The difliculty heretofore has been that in adjusting the burrs for finer grinding or reduction, the outlet' portions of the burrs approach each other" too rapidly, as compared with the approaclr of the crushing portions of the burrs, and the result is that there is a clogging of the substance at the outlet, which of course results in loss of time, unsatisfactory reduction, and

v undue wear on the burrs which greatly shortens the life thereof, It is this difficulty that I have sought to overcome by modifying the'shape of the burrs near the reduction or outlet end, and this is the ob:

.ject of the present invention. I

My nvention consists in the construct on,

arrangement and combination ofelements hereinafter set forth, pointed out in the claim and illustrated by the accompanying drawing, in which- Figure 1 is a longitudinal section of a portion of a grinding mill equipped with and illustrating my improved form of burrs and showing them in an adjusted position for relatively fine reduction.

Figure 2 is a similar view showing'thc burrs adjusted for extremely coarse reduction.

Figure 3 is a perspective view of the i11- ner burr removed from the mill.

In the construction of the 7 devices as shown the numeral 10 designates generally the frame of a mill which may be of any suitable form and construction and having a feed hopper 11 by which thesubstance to be ground is introduced. Suitably mounted in the frame lO, as by bolts 12, is an outer or stationary burr 13of generally conical form, or rather frusto-conical, of hollow form and provided on its inner surface with any suitable form of teeth orv crushing, grinding and reducing devices. Arranged 1926; Serial no. 114,168.

axially of the outer bin-r13 and suitably journaled in the frame is a shaft 14 adapted to'be rotated by any suitable power. In the present form of the device, in which the burrs are arranged in horizontal position, the shaft 14 is provided with inclined lugs 15 in the throat of'the hopper to carry'the substance'to be ground toward the'burrs as the shaft isrotated; but in the vertical type of mill dependence may be placed upon gravity to cause the substance to so travel.-

Mounted on the shaft 14, within and in a position to cooperate with the outer burr 13, is an inner burr 16, also'of hollow construction.

partially embracing the apex of said inner burr 5s a cap 18, which core and cap are secured to the shaft 14 as by bolts 19 and 20 respectively. p The cap 18'l1olds the apical portion of the burr l6-to the shaft, and the base portion thereof ,is held by means of bolts 21 passing therethrough and through the flange of the core 17.- The adjustment of the inner burr relative to the outer burr is accomplished by shifting the shaft 14 longitudinally by any suitable and common means, not shown. q p q j In this type of grinding mills the taper of the inner burr is more pronouncedt-han thatof the outer so that there is a greater annular space between their apical portions,

construction the taper or slant is uniform from end to end of each burr, or in other words the inner surface of the outer burr and the outer surface of the inner burr are, throughout, true conical elements. MyimlVithin the inner burr 16 "isa core 17 which is flanged at its base, and

provement consists in modifying this construction at the base portions of the burrs by forming such base portions on segments of spheres which merge into the conical elements and continue to the base end of the burrs. With respect to the outer burr, the spherical portion begins substantially at the point a and with respect to the inner burr it begins substantially at the point Z), in both instances continuing to the larger end of the burr, which would be substantially on a diameter of the sphere. It is to be understood that the grinding surfaces of the burrs 13 and 16 are of any suitable type as indicated conventionally in Figure 3, but the indication of these grinding surfaces has been omitted in Figures 1 and 2 in order to show more clearly the true shape of the burrs themselves.

It will be understood with respect to the usual type of burr in which the grindi surfaces are formed throughout on conidiil lines of difl'erent tapers, that as the inner Can burr is adjusted vfor liner reduction, for instance from the position of Figure 2 to that of F igure 1, the base ortions, where the fine grinding occurs, will up roach each other more rapidly than will tie apical ortions, where the coarser reduction or crus1ingoecurs because of the convergence of the surtacos toward the base ends; The result is that the effective grinding surface near the base end is greatly reduced as such adjustment is made, and further that by the surfaces approaching each other at angles the tendency of the .mill to clog is greatly in creased. The :factis that in this type of mill, havinq the usual form of burrs, great dilliculty we been found in ocrating the mill at all when adjusted for line reduction, because vol the constant clogging at the outlet; and further that excessive wear occurs on the relatively small area of the reducing surfaces which is actually used during such adjustment, thus greatly reducing the effec ti ve life of the burrs.

By reason of my peculiar formation of the here or reducing end portions of the loin-rs namely on spherical lines rather than coni cal, when :ltljllStlllGlli' is nuide for instance from the position of Figure 2 to that of Figure 1., such base portionsdo not a ppronch each other as rapidly as they otherwise would, and in fact do not approach as rapidly as do the conical portions toward the mouth ol the mill. This is because in male ing such adjustment ithe spherical surfaces travel toward a position of substantial con ceutricity or to a, position where they are substantially paralleh instead of converging as in the ordinary form. It follows that such adjustment may be made, and finer reduction secured at the crushing end portion of the burrs, without restricting the grind ing surface at the outlet end, or restricting the outlet itself, so that the objectionable tendencies above referred to are overcome. This materially increases the elliciency of the mill, particularly when adjusted for fine reduction, and lengthens the life oi? the burrs.

My improved burrs can be provided with grinding surfaces on their entire faces, and can be adjusted to griml to any desired reduction without clogging, even when the substance to be ground is wet. The burrs may he made each integral or in sections as here shown and can be )rovided with an de sired ,or suitable grinding surfaces. y are peculiarly adapted to grinding all kinds of stock feed and will gr nd faster and mm more easily, because the burrs may be made of less diameter than the usual burrs, and thus being closer to the shaft require less power. They can of course be made in any desired size and. either vertical or horizontal Owing to the greater surface provided for line reduction or finishing of the product being ground the grinding surfaces of the burrs can be run farther apart whichwill save wear on the burrs and Will require less power to run the mill.

I claim as my invention- In a grinding mill, an outer burr and an inner burr cooperating therewith, one of said burrs hein rotatable and longitudinnlly adjustable, said lJlUIH having their apical portioiri-i of substantially conical formation and without curvature longitudinally and converging toward their delivery ends and having their base portions formed substantially as spherical segments. whereby when adjustment lliiltlc for liner reduction the conical surfaces will :uiproach each other inore rapidly than the spherical surfaces.

THEODORE \VAD'LEIUH. 

